1. Field of the Invention
The invention relates, generally, to a cutting unit, and more specifically, to a printing system or folder incorporating the cutting unit.
2. Description of the Related Art
In the art of printing systems, folders are used to cut signatures having varying lengths. In order to decrease the length of the signature, it is necessary to increase the angular velocity ratio between the folder and the printing units. As a result, the velocity of the signature is increased after it is cut. The increased velocity of the signature is counterproductive to downstream transport and deceleration functions. Therefore, the signature must be engaged by a deceleration mechanism for decelerating the signature before the signature can be further processed. Unfortunately, there is the inherent risk of damaging the signatures (i.e. dog-earing) and/or jamming the folder whenever the custody of the signature must be transferred from one machine component to another, i.e. from a transport unit to a deceleration unit. Therefore, it is desirable to limit the number of signature transfers occurring throughout the printing process.
The prior art folders are also known to cut the signature with a raking action of a serrated knife. The serrated knife thereby producing a saw-tooth (ragged) cut. The ragged cut is not desirable in the final product and therefore a subsequent trimming process is usually required to put the product in final form with a smooth edge.